Sensitivity of proton implanted VCSELs to electrostatic discharge pulses

The sensitivity of vertical cavity surface-emitting lasers to electrostatic discharge (ESD) pulses has been investigated under human body model test conditions. Very similar degradation behavior has been found for vertical-cavity surface-emitting lasers (VCSELs) from two different manufacturers, both with proton-implantation for lateral current confinement. For all investigated devices we observed during forward bias stress that the optical degradation precedes the electrical degradation and the forward bias damage threshold pulse amplitudes were only slightly higher than the reverse bias values. At the initial stage of the VCSEL degradation, damage of the upper p-DBR mirror region has been observed without modification of the active layer. During the ESD tests we monitored the electrical and the optical parameters of the VCSELs and measured during forward bias stress additionally the optical emission transients. The optical transients during ESD pulsing enable a fast evaluation of the damage threshold and give also an indication of the time scale of the junction heating during ESD pulses.